Preheat oven to 350°F. Grease a 9-by-9-inch pan with shortening, then coat with cocoa powder. Set aside.

Place butter, 1/2 pound chocolate chips, and unsweetened chocolate in top of a double boiler or in a heat-proof bowl set over a pan of simmering water until melted and smooth, stirring frequently. Cool slightly. In a large mixing bowl, combine eggs, chocolate syrup, vanilla, and sugar. Add mixture to warm melted chocolate and cool.

In a separate mixing bowl, combine 1/2 cup flour with baking powder and salt, then stir into chocolate mixture. In another mixing bowl, combine macadamia nuts and remaining 1/2 pound chocolate chips with 2 tablespoons flour until nuts and chips are coated. Add nuts, chips, and coconut to chocolate mixture and combine thoroughly. Pour mixture into the prepared pan.

Bake for 12 minutes. Remove pan from oven, tap it several times to remove air from brownies. Continue to bake for another 12 to 15 minutes, or until a toothpick inserted into the middle comes out clean. Cool completely.

Make the sauce by placing chopped chocolate in a medium-sized mixing bowl. Place cream in a small saucepan over medium heat and bring just to a boil. Immediately remove from heat and pour over the chocolate and stir until smooth. Add the vanilla and stir until combined.

Cut brownies into 8 large squares and place on serving plates. Top each with two scoops of ice cream (about 1/2 cup), ladle with chocolate sauce to taste, and sprinkle with toasted coconut and powdered sugar. Garnish with mint leaves and serve immediately.